ChemInform Abstract: Synthesis of ω‐Hydroxy Analogues of Valine, Leucine and Isoleucine.

Abstract

267ChemInform Abstract The allo and iso isomers (V) and (VI) of γ-hydroxy valine are prepared by a modified Erlenmeyer synthesis; the reaction sequence involves chromatographic separation of the E-and Z-oxazolinones (III) and (IV) and subsequent conversion of the isomers into racemic allo-or iso-γ-hydroxy valine (V) or (VI) as shown for (V). The optical resolution of each isomer (V) or (VI) to give the corresponding D-or L-enantiomers is achieved enzymatically using L-or D-amino acid oxidase. The δ-hydroxy analogues (XIIa) and (XIIb) of leucine and isoleucine are synthesized via 1,4-Michael addition; the diastereomers of (XIIb) are separated by reverse phase HPLC (allo RR, SS and iso RS, SR).